Experimental and Theoretical Fracture Analysis of Anisotropic Elastomers via Direct Ink Writing

This paper presents an investigation into the fracture mechanics of additively manufactured elastomers through an integrated theoretical and experimental approach. Elastomeric specimens with varying print orientations are fabricated using direct ink writing (DIW). Tensile tests on both uncracked and pre-cracked specimens are conducted to characterize the mechanical and fracture behavior of the printed elastomers, revealing significant anisotropy resulting from the layer-by-layer nature of DIW. To address this anisotropy, data from tensile experiments on uncracked specimens are used to calibrate an anisotropic constitutive model, which is implemented in finite element simulations to analyze the mixed-mode fracture behavior of pre-cracked specimens. The results indicate that while the critical J-integral varies with print orientation, its ratio to the effective critical distance remains constant, introducing a novel critical parameter for fracture analysis of anisotropic elastomers. This study establishes a novel methodology for exploring fracture mechanics in 3D printed elastomers and underscores the potential of DIW in advancing the design and manufacturing of high-performance anisotropic soft materials.